The present invention relates to a process for the preparation of 1,4-naphthoquinone-- hereafter referred to, for brevity, as naphthoquinone-- by reaction of naphthalene with molecular oxygen in the gas phase in the presence of a catalyst containing vanadium.
Naphthoquinone is a valuable intermediate product for the preparation of anthraquinone (see German Published Application 2,218,316).
It is known from Belgian Patent 798,181 to react naphthalene in the gas phase with molecular oxygen in the presence of a catalyst containing vanadium, to give naphthoquinone and phthalic anhydride. It is also known, from the same patent specification, to carry out the reaction of naphthalene to naphthoquinone by passing a gas mixture consisting essentially of nitrogen, oxygen, water vapour, carbon dioxide and naphthalene under pressure at elevated temperature through a reactor in which a catalyst, containing vanadium, is located in reaction tubes arranged in parallel.